A semiconductor device such as a conventional board mounting thereon a digital, analog, and RF mixing circuit, an SOC (system on chip), or a pseudo SOC has a problem in which mutual electromagnetic field interference between elements and noises propagating to a GND (ground) line and a power line cause malfunction. To avoid this problem, a large space needs to be taken between the elements. This has been caused a problem of difficulty in reducing a chip area and an assembly area.
As an exemplary means for reducing this space, a filter that prevents noises in a harmful frequency range to circuit operations propagating to the GND line or the power line is used, for example. In this case, a filter that lowers a noise level in a stopband range, which is a limited frequency range, is used. The filter is formed with use of an inductor chip and a capacitor chip, for example. This inevitably leads to an increase in the number of assembling components.
Under such circumstances, an EBG (Electromagnetic Band Gap) structure in a dielectric board is proposed since it exerts a greater size-reduction effect than forming a filter by chip components. However, the EBG structure still has a problem of not being able to reduce the size since the EBG structure is enlarged in a case where the stopband range is set to a low frequency range (6 GHz or lower). The EBG structure also has a problem of difficulty in securing a wide stopband range.
To cope with this, efforts to improve the EBG structure are being made in order to reduce the size of the EBG structure.